import { Score } from '../shared/types.js';

export interface ConflictResult {
  accept: boolean;
  reason?: string;
}

/**
 * Determine whether an incoming score should be accepted over an existing one.
 * Uses last-write-wins strategy based on updatedAt timestamps.
 *
 * - If no existing score → accept
 * - If incoming.updatedAt > existing.updatedAt → accept (last-write-wins)
 * - If incoming.updatedAt <= existing.updatedAt → reject
 */
export function shouldAcceptScore(
  incoming: Score,
  existing: Score | undefined
): ConflictResult {
  if (!existing) {
    return { accept: true };
  }

  if (incoming.updatedAt > existing.updatedAt) {
    return { accept: true };
  }

  return { accept: false, reason: 'Newer score already exists' };
}

/**
 * Resolve a score conflict with optional force override.
 *
 * - If force is true → always accept
 * - Otherwise delegate to shouldAcceptScore (last-write-wins)
 */
export function resolveConflict(
  incoming: Score,
  existing: Score | undefined,
  force?: boolean
): ConflictResult {
  if (force) {
    return { accept: true };
  }

  return shouldAcceptScore(incoming, existing);
}